Movable fence for a machine tool

ABSTRACT

An adjustable rip fence for a machine tool has a fence which is movable with respect to the cutting tool due to a rack and pinion. The rail assembly supporting the fence include a pair of stationary rails which are secure to the machine tool. A movable rail telescopically engages each stationary rail and the movement of each rail is accomplished by the rotation of a pair of pinion gears each of which engages a respective rack on the movable rails. The simultaneous rotation of the pinion gears is the result of both pinion gears being secured to a common pinion shaft which is rotatably secured to the machine tool. The telescoping nature of the rails allows for adjustment of the fence beyond the working surface of the machine tool.

This application is a continuation of application Ser. No. 08/541,389,filed Oct. 10, 1995, now U.S. Pat. No. 5,722,308.

FIELD OF THE INVENTION

The present invention relates to work guiding systems for machine tools.More particularly, the present Invention relates to a movable rip-fencefor a table saw, band saw or the like which maintains a parallelrelationship with the cutting blade during movement and/or adjustment ofthe position of the movable rip-fence.

BACKGROUND OF THE INVENTION

A typical table saw Includes a base which supports a generally flattable top having a longitudinally extending slot and a pair of siderails extending along opposite sides of the table top generallyperpendicular to the slot. The side rails are utilized for mounting arip fence assembly to assist in positioning an article to be cut Inrelation to a cutting tool. A motor is mounted beneath the table top andthe cutting tool, which may be a circular saw blade, is mounted forrotation with the output shaft of the motor. The cutting tool ispositioned to project upwardly through the slot and is rotated by themotor in a plane which is generally perpendicular to the axis of theside rails. Cutting of the workpiece is normally accomplished by movingthe workpiece longitudinally through the saw blade as it is rotating.

Table saws are used for cross cutting (transverse cutting to the lengthof the workpiece), bevel cutting (at an angle to the length of theworkpiece) and rip cutting (longitudinal cutting along the length of theworkpiece). For cross cutting and bevel cutting, an angularly andlaterally adjustable fixture or fence is used which positions theworkpiece perpendicular to or at the desired angle relative to the sawblade. For rip cutting, the separate rip fence assembly mounted on theside rails must be used in order to position the workpiece in thedesired location which is generally parallel to the saw blade in orderto perform the longitudinal or rip cutting operation on the workpleoe.

The rip fence assembly helps in making the parallel rip cuts by guidingthe workpiece longitudinally through the cutting tool while one edge ofthe workpiece is maintained In abutting relationship with the rip fenceassembly. The rip fence assembly normally includes an elongated ripfence which extends between the two side rails of the base of the tablesaw. The elongated rip fence is generally perpendicular to the siderails and thus parallel to the cutting tool and/or cutting direction.The rip fence assembly typically includes a pair of fence guides securedat opposite ends of the rip fence, each of which is adapted to engage arespective side rail for sliding movement therealong.

During the movement and subsequent securing of the rip fence assemblyalong the side rails, it is necessary to keep the rip fence parallel tothe plane of the saw blade in order to ensure the straightness of thecut and to avoid oblique angles between the said blade and the directionof cut. Even minor variations in such parallelism can lead to anunacceptable degree of error in the cutting of material to be used forvarious applications and the possibility of binding the cutting toolwithin the kerf being cut into the material. The problem of maintainingparallelism is magnified if one attempts to remove the rip fenceassembly, for example to cut a large piece of stock such as a sheet ofplywood or a fiberboard sheet, and then replace the rip fence assemblyto resume the cutting of smaller pieces.

Prior art rip fence assemblies have worked well in securing the ripfence assembly to the side rails in order to position a workpiecerelative to the cutting tool, while also permitting the rip fenceassembly to be property and accurately adjusted relative to the cuttingtool for accurate longitudinal or rip cutting. Most of the problems thathave arisen in connection with the prior art rip fence assemblies relateto adjusting the rip fence while simultaneously maintaining the ripfence in a parallel relationship to the cutting tool. In addition to theproblems of parallelism, the rip fence assembly must be conveniently andquickly removed and subsequently reinstalled while still maintaining itsrelative positional relationship with the cutting tool. Some prior artsystems do provide for the removal and replacement of the fence, butsuffer a loss of parallelism in the process. Other prior art systemsmaintain parallelism of the fence but are difficult to remove andre-install.

Another problem associated with prior art rip fence assemblies andmachine tools has been the width of permissible cut. When a machine toolor table saw is permanently located, it is a simple matter to provideextensions to the table top which have side rails which mate with theside rails of the machine tool or table saw to permit the adjustment ofthe rip fence assembly to allow virtually an unlimited width ofpermissible cut. When using a portable machine tool or table saw, theincorporation of table top extensions with the required accuracy ofpositioning the extensions, makes it unrealistic to continuouslyassemble and disassemble the various extensions as the machine tool ortable saw is carried from one job site to another. Thus, a portablemachine tool or table saw has the additional problem of adjusting therip fence assembly to a position which allows for a maximum width of cutwithout the need for incorporating table top extensions or the like.

The continued development of rip fence assemblies is directed towards ahighly accurate rip fence assembly which may be quickly and accuratelysecured in any desired position on the work table of a machine tool ortable saw. The rip fence assembly should be capable of accuratepositioning relative to the cutting blade as well as having a sufficientadjustment in the width of the cut to permit a wide cutting widthwithout the need for incorporating table top extensions. The improvedrip fence assembly should be relatively inexpensive to manufacture,simple and compact in construction and be suitable for use on machinetools or table saws adapted for both stationary and portable use ineither a commercial or a home workshop environment.

SUMMARY OF THE INVENTION

The present invention provides the art with an adjustable rip fenceassembly which maintains its positional relationship with the cuttingtool during the adjustment of the width of cut. The width of cut isadjustable beyond the width of the table top without the need forextensions being added to the table top. The rip fence assemblycomprises a rip fence which is adjustably secured to a front and rearrail assembly utilizing a front and a rear bracket. The front and rearrail assembly comprise a telescoping rail which is movable utilizing arack and pinion assembly or a cable and a pulley system. In the rack andpinion assembly, each rail is provided with a rack which matinglyengages a pinion. Both the front and rear pinions are secured forrotation on a common axle shaft such that rotation of the axle shafttranslates into longitudinal parallel movement of the rip fence. The ripfence is first adjusted to be both plumb and parallel to the cuttingtool utilizing the adjustable connections between the front and rearbrackets and the respective rail assemblies. Once properly positioned,the rip fence can be adjusted to set the desired width of cut whilestill maintaining its positional relationship to the cutting tool due tothe simultaneous movement of the front and rear racks by the common axleshaft and the front and rear pinion gears. In the cable and pulleysystem, opposite ends of opposing telescoping rails are connected toeach other with the cable being routed through a series of pulleys suchthat the rip fence will maintain its positional relationship to thecutting tool due to the simultaneous movement of the telescoping railscaused by the cables and pulleys. The telescoping feature of the frontand rear rail assemblies permit the width of cut to significantly exceedthe width of the table top. When the rip fence assembly is positionedoff of the work table, a pivotable work support is positioned adjacentto the rip fence to provide a supporting surface which is co-planar withthe table top.

The present invention allows the fence assembly to be moved over a rangeof lengths which exceeds the length of the stationary rails. The fenceassembly may be positioned outwardly of at least one side edge of thework table without requiring that the stationary rails extend outwardlyof this side edge. Preferably, the fence assembly can be moved beyondthe width of the work table, outwardly of either side edge, withoutrequiring that the stationary rails have a length which is greater thanthe width of the table to provide for such movement. Further, the fencemay be connected to both front and rear movable rails whichtelescopically engage and slide over front and rear stationary rails.The front and rear movable rails are interconnected, for example, by arack and pinion mechanism or a system of cables and pulleys, whichensure that movement of one movable rail causes an equal movement of theother movable rail. Thus, the fence may be maintained parallel to thesaw blade as it is moved relative thereto.

Other advantages and objects of the present invention will becomeapparent to those skilled in the art from the subsequent detaileddescription, appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings which illustrate the best mode presently contemplatedfor carrying out the present invention:

FIG. 1 is a perspective view of a table saw incorporating a unique rackand pinion fence assembly according to the present invention;

FIG. 2 is a perspective view of the telescoping rack and pinion fenceassembly illustrated in FIG. 1;

FIG. 3 is a plan view, partially in cross section, of the table saw andthe rack and pinion fence assembly illustrated in FIG. 1;

FIG. 4 is a side elevational view of the table saw and the rack andpinion fence assembly illustrated in FIG. 1;

FIG. 5 is a blown apart perspective view illustrating the sliding pinmount on the proximate foot of the fence mounts in accordance with thepresent invention;

FIG. 6 is a side elevational view, partially in cross section, of thesliding pin mount on the distal foot of the fence mounts of the presentinvention;

FIG. 7A is a top plan schematic view showing the adjustability of thesliding pin mount shown in FIG. 5;

FIG. 7B is a side elevation schematic view showing the adjustability ofthe sliding pin mount shown in FIG. 6;

FIG. 8 is a perspective view, partially in cross section, of the tablesaw with only the fixed inner rails and the pinion shaft assembly beingsecured to the work table;

FIG. 9 is a side elevational view, partially in cross section, of thetelescoping rail of the present invention showing the attachment of theinner rails and the pinion shaft to the table saw;

FIG. 10A is an enlarged schematic presentation of the cutting widthindicating mechanism of the present-invention shown at a 0" cuttingwidth;

FIG. 10B is an enlarged schematic presentation of the cutting widthindicating mechanism of the present invention shown at a 9" cuttingwidth;

FIG. 10C is an enlarged schematic presentation of the cutting widthindicating mechanism of the present invention shown at a 20" cuttingwidth;

FIG. 11A is a perspective schematic of the rip fence assembly of thepresent invention modified to meet European standards with the rip fencemounted in the right hand side of the cutting tool;

FIG. 11B is a perspective schematic of the rip fence assembly of thepresent invention modified to meet European standards with the rip fencemounted in the left hand side of the cutting tool;

FIG. 12A is a side elevational view of a rack illustrating a method oflimiting the travel of the rack with respect to the pinion;

FIG. 12B is a side elevational view of a rack and pinion gearillustrating the travel limitation feature shown in FIG. 12A;

FIG. 13 is a perspective view similar to FIG. 2 but showing anotherembodiment of a telescoping rack and pinion assembly according to thepresent invention;

FIG. 13A is a perspective view of a fence mount shown in FIG. 13;

FIG. 14 is a perspective view showing the adjustability of the rack andpinion assembly shown in FIG. 13;

FIG. 14A is a bottom view of the adjustment system shown in FIG. 14 withthe fence being in a non-parallel position with respect to the sawblade;

FIG. 14B is a bottom view similar to 14A but showing the table saw afteradjustment of the fence to a position parallel to the saw blade;

FIG. 15 is a side elevation al view partially in cross-sectionillustrating the locking mechanism for the rack and pinion assemblyshown in FIG. 13 with the mechanism in the unlocked position;

FIG. 16 is a side elevational view partially in cross-section similar toFIG. 15 but with the locking mechanism shown in the locked position;

FIG. 17 is a plan view of the locking mechanism shown in FIGS. 15 and16;

FIG. 18 is a perspective view illustrating the locking pivotableconnections utilized in the locking mechanism shown in FIGS. 15 through17;

FIG. 19 is a perspective view similar to FIG. 18 but illustrating thelocking pivotable connection in its locked position;

FIG. 20 is a side elevational view, partially in cross-section, of thetelescoping rail of the rack and pinion assembly shown in FIG. 13illustrating the attachment of the inner rails and the pinion shaft tothe table saw;

FIG. 21 is a perspective view of the connection between the fence andthe fence mount of the rack and pinion fence assembly shown in FIG. 13;

FIG. 21A is a side view of the over-center latch which locks the fenceassembly to the movable rails with the latch in its closed position;

FIG. 21B is a side view similar to FIG. 21A but showing the over-centerlatch in its open position;

FIG. 21C is an exploded side view of the fence assembly and the worktable of the present invention showing the incorporation of a biasingspring;

FIG. 21D is a perspective view of the biasing spring shown in FIG. 21C;

FIG. 22 is a perspective view of the pivotable workpiece support for therack and pinion assembly of the present invention;

FIG. 23 is a longitudinal cross-sectional view of the pivotableworkpiece support and the fence shown in FIG. 22 illustrating thelocking feature for the support;

FIGS. 24A and 24B are schematic illustrations of the telescoping fenceassembly according to the present invention;

FIGS. 25A and 25B are enlarged perspective views illustrating the shimsschematically shown in FIGS. 24A and 24B;

FIG. 26 is a partial perspective view of the stationary rail accordingto the present invention incorporating a wedge to provide an adjustableshim;

FIG. 27 is a perspective view showing the telescoping rack and pinionassembly of FIG. 13 and also sharing a further embodiment of a cuttingwidth indicating mechanism;

FIG. 28 is a blown apart side view of a spring loaded bearing mount inaccordance with the present invention;

FIG. 29 is an end view of the spring loaded bearing mount shown in FIG.28 in the assembled condition;

FIGS. 30A-30C illustrate a telescoping rail assembly according to thepresent invention incorporating cables and pulleys for ensuringsimultaneous movement of the two movable rails;

FIG. 31A Illustrates a cable and pulley telescoping rail assemblyaccording to another embodiment of the present invention;

FIG. 31B is an enlarged view of the tension adjustment pulley assemblyshown in FIG. 31A;

FIG. 31C is an enlarged view of the alignment adjustment pulley assemblyshown in FIG. 31A; and

FIGS. 32A-32C are perspective views illustrating additional embodimentsof a rack and pinion adjustable fence assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in which like reference numerals designatelike or corresponding parts throughout the several views, there is shownin FIG. 1 a table saw which is designated generally by the referencenumeral 10 incorporating a unique rack and pinion fence assemblyaccording to one embodiment of the present invention. While the rack andpinion fence assembly of the present invention is being illustrated forexemplary purposes as being used in conjunction with table saw 10, it iswithin the scope of the present invention to incorporate the rack andpinion fence assembly of the present invention into any type of machinetool which utilizes a fence. For example, the invention could beutilized with a band saw, a scroll saw, drill press, drum sander orrouter table.

Referring to FIGS. 1 through 4 table saw 10 comprises a base 12 whichsupports a generally rectangular work table 14. Work table 14 includesan insert 16 which includes an elongated slot 18 through which a rotarycutting tool such as a circular saw blade 20 protrudes. Saw blade 20 isnormally capable of being adjusted for depth of cut and angularity withrespect to work table 14 by a control knob (not shown) and a controllever (not shown), respectively. Table saw 10 illustrated in FIGS. 1, 3and 4 is a portable table saw which is easily movable from one job siteto another. Table saw 10 can easily be picked up and carried utilizingwork table 14 as the supporting locations when it becomes necessary tolift and carry table saw 10 from one job site to another.

One embodiment of the present invention is directed towards a uniquerack and pinion fence assembly 30 which is deployable beyond theenvelope of work table 14 in order to provide additional width for thecutting operation but yet maintaining a compact envelope for simplifyingtransportation of table saw 10. The compact envelope of table saw 10facilitates both storage of table saw 10 and the movement of table saw10 from one job site to another.

Rack and pinion fence assembly 30 comprises an elongated fence body 32,a pivotable support member 34, a front fence mount 36, a rear fencemount 38 and a pair of telescoping tubular side rail assemblies 40 and42. Fence body 32 is an elongated generally rectangular member whichprovides a flat guide surface 44. Fence body 32 is sized to extendbeyond both a front and a rear longitudinal edge 48 and 50,respectively, of work table 14. Referring now to FIG. 5, fence body 32is fixedly secured at its opposite ends to front fence mount 36 and rearfence mount 38 using a plurality of bolts 52. Pivotable support member34 is pivotably secured to both front and rear fence mounts 36 and 38and extends between mounts 36 and 38 as shown in FIGS. 1 through 4. Whenfence body 32 is adjusted to provide a relatively wide cut, fence body32 extends beyond the surface of work table 14 as shown in FIGS. 1, 3and 4. In this situation, conventional table saws do not provide supportfor the workpiece at a point directly adjacent to fence body 32. Theonly support for the workpiece would be the surface of work table 14which can be a substantial distance from fence body 32. In table saw 10,pivotable support member 34 provides a surface for supporting theworkpiece adjacent to fence body 32 when support member 34 is positionedin its lower position as shown in FIGS. 1 through 4. The supportingsurface of pivotable support member 34 is designed to be coplanar withthe top surface of work table 14 when support member 34 is in itslowered position. When fence body 32 is adjusted to provide a relativelynarrow cut, fence body 32 will be positioned over the surface of worktable 14 and there is no need for pivotable support 34 as the workpiecewill be supported by the surface of work table 14 directly adjacent tofence body 32. In this narrower cutting application, pivotable support34 is moved to its upper position, shown in phantom in FIGS. 1, 2 and 4,and fence body 32 functions with work table 14 in a normal manner.

Referring now to FIGS. 5 and 6, front and rear fence mounts 36 and 38are adapted to adjustably secure fence body 32 to the pair oftelescoping tubular side rail assemblies 40 and 42. FIGS. 5 and 6illustrate only front fence mount 36. Front fence mount 36 and rearfence mount 38 are identical except for being mirror images of eachother. It is to be understood that rear fence mount 38 incorporates thesame adjustment features that are provided in front fence mount 36.Front fence mount 36 and rear fence mount 38 are each a plate-likemember defining a proximate foot 54 which is adjacent fence body 32 anda distal foot 56 which is distal of fence body 32. The adjustablemounting of front and rear fence mounts 36 and 38 provides adjustmentfor the plumbness of fence body 32 as well as adjustment for theparallelism of fence body 32 relative to saw blade 20. The adjustmentfor the parallelism of fence body 32 ensures that it will be parallel inthe horizontal plane to the plane of saw blade 20, as shown in FIG. 7A,and is accomplished using an adjustment mechanism 58 on proximate foot54. The adjustment for the plumbness of fence body 32 ensures that Hwill be parallel to the plane of saw blade 20 in a vertical plane, shownin FIG. 7B, and is accomplished using an adjustment mechanism 60 ondistal foot 56.

Referring now to FIG. 5, adjustment mechanism 58, on proximate foot 54,comprises a bolt 62 and a pin mount 64. Proximate foot 54 defines anotch 66 which extends upward from the bottom of proximate foot 54.Extending into the portion of proximate foot 54 defined by notch 66 is acavity 68 having a semicircular cross-section within which bolt 62 islocated. Bolt 62 includes a front annular groove 70 and a rear annulargroove 72 which mate with a front and rear annular shoulder 74 and 76,respectively, located at opposite ends of cavity 68. Thus, bolt 62 istrapped within cavity 68 by the engagement of grooves 70 and 72 withshoulders 74 and 76, but bolt 62 is free to rotate within cavity 68 dueto the lack of screw threads on the internal surface of cavity 68. Pinmount 64 is a generally L-shaped member which is disposed within notch66. Pin mount 64 includes a cavity 78 having a semi-circularcross-section which defines a plurality of threads 80 which threadinglyengage bolt 62. Pin mount 64 is secured to proximate foot 54 by a nut 82and bolt 84 which extend through a hole 86 in proximate foot 54 and acorresponding slot 88 extending through sliding pin mount 64. A mountingpin 90 extends vertically from the bottom surface of mount 64 and isdesigned to engage any one of a plurality of corresponding apertures 134located within front or rear telescoping side rail assembly 40 and 42Once assembled, rotation of bolt 62 forces relative longitudinalmovement of front fence mount 36 along pin mount 64 due to the fact thatmounting pin 90 is disposed within the corresponding aperture 134, andthat bolt 62 is trapped within cavity 68 and engaged with the pluralityof threads 80 located in cavity 78 of pin mount 64. Thus, fence mount 36undergoes longitudinal movement along rail assembly 40 or 42 while fencemount 38 remains stationary. This longitudinal movement of fence mount36 relative to fence mount 38 will adjust the parallelism of fence body32 with respect to saw blade 20 by causing rotation of fence body 32about a vertical axis as shown in FIG. 7A.

Referring now to FIG. 6, adjustment mechanism 60 on distal foot 56comprises a set screw 92 and a mounting pin 94. Distal foot 56 defines athreaded bore 96 which extends completely through distal foot 56. Setscrew 92 is threadingly received within bore 96 and mounting pin 94 isslidingly received within bore 96 and extends vertically through thelower surface of distal foot 56 to support front fence mount 36 or rearfence mount 38 on front or rear telescoping side rail assemblies 40 or42. Set screw 92 may be accessed by a screwdriver or a wrench from theupper opening of base 96. The rotation of set screw 92 in one directionwill increase the vertical distance that mounting pin 94 extendsdownwardly from distal foot 56 and rotation of set screw 92 in theopposite direction will decrease the vertical distance that mounting pin94 extends downwardly from distal foot 56. The vertical movement ofmounting pin 94 with respect to distal foot 56 will adjust the plumbnessof fence body 32 with respect to saw blade 20 as shown in FIG. 7B.Mounting pin 94 is maintained within bore 96 due to the slidingrelationship between pin 94 and bore 96 or, if desired, pin 94 may bemanufactured as an integral part of set screw 92.

The adjustment of fence body 32 and front and rear fence mounts 36 and38 begin by locating mounting pin 90 of front fence mount 36 in any oneof the corresponding apertures 134 located within front or reartelescoping side rail assemblies 40 or 42. Mounting pin 90 of rear fencemount 38 is also located in any one of the corresponding apertures 134located on the opposite telescoping side rail assembly 40 or 42. Theorientation of fence body 32 and front and rear fence mounts 36 and 38will be determined by the side of saw blade 20 upon which fence body 32is to be located. Once positioned on side rail assemblies 40 and 42,fence body 32 is supported by front and rear fence mounts 36 and 38which are positioned on side rail assemblies 40 and 42 by proximate feet54 and the pair of mounting pins 94 extending out of rear feet 56.

The parallelism of fence body 32 with respect to saw blade 20 may bedetermined by moving fence body 32 to a position adjacent to the sawblade itself or adjacent to a groove machined into work table 14, or byusing a T-square or any other means to determine the parallelism offence body 32 with respect to saw blade 20. The parallelism may beadjusted by rotating either or both bolts 62, causing the movement offence mount 36 as discussed above. This movement will rotate fence body32 about a vertical axis 97 if both bolts 62 are adjusted, or about avertical axis 97a if only bolt 62 of front mount 36 is adjusted, orabout a vertical axis 97b if only bolt 62 of rear mount 38 is adjustedas shown in FIG. 7A. Once the parallel position of fence body 32 hasbeen adjusted, nuts 82 are tightened on bolts 84 on both front and rearfence mounts 36 and 38 to lock each sliding pin mount 64 within itsrespective notch 66. While the above description has defined both frontand rear fence mounts 36 and 38 as having adjustment mechanism 58, it iswithin the scope of the present invention to only have one of front andrear fence mounts 36 and 38 equipped with adjustment mechanism 58 andthe other mount being equipped with a fixed mounting pin 90. Equippingonly one of fence mounts 36 and 38 with adjustment mechanism 58 wouldreduce the amount of adjustment due to the fact that only one slot 88would be available for adjustment.

Once the parallelism of fence body 32 has been set, the plumbness can beadjusted using saw blade 20, a right-angle square or any other means ofdetermining the plumbness of fence body 32. Adjustment of the plumbnessof fence body 32 is accomplished by rotating the pair of set screws 92to change the vertical extension of both mounting pins 94 extending fromrear feet 56. This movement will rotate fence body 32 about a horizontalaxis 99 as shown in FIG. 7B. Once the plumbness of fence body 32 hasbeen adjusted, the position of set screws 92 within threaded bore 96 canbe maintained by providing locking nuts or screws or by any other meansknown well in the art.

Upon the completion of both the parallelism and plumbness adjustments offence body 32, an over-center latch 98 secures fence body 32 and frontand rear fence mounts 36 and 38 in position on front and rear side railassemblies 40 and 42 by engaging a keeper 100 fixedly secured to frontand rear side rail assemblies 40 and 42. Over-center latch 98 is wellknown in the art and will not be discussed further within thisspecification.

Referring now to FIGS. 2, 3, 8 and 9, front and rear telescoping tubularside rail assemblies 40 and 42 are each comprised of an inner rail 110,and an outer rail 112. A pinion shaft assembly 114 extends between andengages side rail assemblies 40 and 42. Inner rails 110 are generallycircular shaped tubular members having a specified length which, in thepreferred embodiment, is generally equal to the width of work table 14.Inner rails 110 are fixedly secured to work table 14 using a pluralityof fasteners 116 which are spaced along the entire length of inner rail110. As shown in FIG. 9, fasteners 116 include a bolt 118, a nut 120 anda bushing 122. Bolt 118 extends through inner rail 110 and through abracket 124 which is secured to or is an integral part of work table 14.Bushing 122 is preferably made from UHMW-PE material and is locatedbetween inner rail 110 and bracket 124 with the assembly being securedby nut 120 being threadingly received on bolt 118. Bushing 122 mayextend over the entire length of inner rail 110. An access hole 126 foreach bolt 118 extends through inner rail 110 to provide access to therespective bolt 118. Inner rail 110 of side rail assembly 40 is fixedlysecured to the front of work table 14 generally parallel to front edge48 of work table 14 while an identical inner rail 110 of side railassembly 42 is fixedly secured in a similar manner to the rear of worktable 14 generally parallel to rear edge 50. Both inner rails 110 extendalong the entire width of work table 14 to provide the maximum amount ofsupport for outer rail 112 while still maintaining a minimized envelopefor table saw 10 for both storage and portability.

Outer rail 112 is a generally U-shaped tubular member which is slidinglyreceived over inner rail 110. Outer rail 112 includes a pair of ribs 130which are adapted to mate with each bushing 122 by being slidinglyreceived within a groove 132 extending into each bushing 122. Theexternal surface of each outer rail 112 is adapted to locate and securefront and rear fence mounts 36 and 38 relative to outer rail 112 usingapertures 134. The plurality of apertures 134 extend through the uppersurface of each outer rail 112 and are sized to freely receive mountingpin 90 of pin mount 64 of adjustment mechanism 58. The distance betweenany two apertures 134 is designed to be different than the distancebetween pins 90 and 94 of adjustment mechanism 58 and adjustmentmechanism 60, respectively. Accordingly, when pin 90 is inserted in oneof the apertures 134, the respective mounting pin 94 of adjustmentmechanism 60 will always contact the upper surface of outer rail 112 andcannot be inserted into any of apertures 134. The plurality of apertures134 are provided in order to allow the manual positioning of front andrear fence mounts 36 and 38 along the entire length of outer rail 112 onboth the left and right sides of saw blade 20 to maximize theversatility of fence assembly 30. Outer rail 112 further includes keeper100 secured to the outside surface of outer rail 112 and extending overthe entire length of outer rail 112. Keeper 100 is adapted to mate withover-center latch 98 to secure front and rear fence mounts 36 and 38 toouter rail 112 once their final position has been determined. Onceover-center latch 98 has been secured, further adjustment of fencemounts 36 and 38 is prohibited.

As shown in FIG. 9, outer rail 112 also includes a rack 140 which isfixedly secured to the bottom surface of outer rail 112 and extends overits entire length. Rack 140 has a trapezoidal shaped cross section whichis slidingly received in a dove-tailed groove 142 located within outerrail 112. Once positioned within groove 142, a plurality of staked areas(not shown) are formed into outer rail 112 to secure rack 140 relativeto outer rail 112. Rack 140 further includes a plurality of rack teeth146 which extend over the entire exposed surface of the rack. Rack teeth146 are designed to mate with pinion shaft assembly 114 as detailedbelow. While rack 140 is being illustrated as a separate componentsecure to outer rail 112, it is within the scope of the presentinvention to have rack 140 integral with outer rail 112 if desired.

Referring now to FIGS. 1 through 4 and 9, pinion shaft assembly 114comprises a pinion shaft 150, a pair of pinion gears 152 and anadjustment wheel 154. Pinion gears 152 and adjustment wheel 154 arefixedly secured to pinion shaft 150 for rotation therewith. Pinion shaft150 is rotatably secured to base 12 such that pinion gears 152 are eachengaged with rack teeth 146 on each outer rail 112 with adjustment wheel154 extending beyond the front outer rail 112 for accessibility by anindividual. Thus, rotation of adjustment wheel 154 causes rotation ofpinion shaft 150 and pinion gears 152 which, due to their engagementwith rack teeth 146 of rack 140, cause longitudinal movement of eachouter rail 112 with respect to each inner rail 110 and the movement offence body 32 relative to saw blade 20. Due to the fact that both frontand rear pinion gears 152 rotate simultaneously and by the same amountdue to their rotation with pinion shaft 150, both front and rear outerrails 112 will move together and the same distance due to the engagementof rack teeth 146 of each rack 140 with a respective pinion gear 152.The simultaneous and equal movement of each outer rail 112 will thusensure that-the relationship between fence body 32 and saw blade 20 willbe maintained during the adjustment of the width of cut for table saw10.

The rotatable mounting of pinion shaft 150 to base 12 permits both therotation of pinion shaft 150 relative to base 12 and the verticallongitudinal movement of pinion shaft 150 with respect to base 12 in adirection which is generally perpendicular to the axis of outer rails112 and racks 140. A pair of coil springs 156 are located between base12 and pinion shaft 150 normally biasing pinion shaft 150 towards racks140 and thus pinion gears 152 into biased engagement with rack teeth 146of racks 140. This biasing of pinion shaft 150 towards racks 140 ofouter rails 112 operates to improve the accuracy of the paralleladjustment of fence assembly 30 by removing any lash between the variouscomponents. The biasing of pinion shaft 150 will remove the lash betweenpinion gears 152 and racks 140 as well as the lash between outer rails112 and inner rails 110.

FIGS. 10A through 10C illustrate a width cut dimensional indicator 160which is incorporated into rack and pinion fence assembly 30 in order toprovide an accurate reading for the distance between fence body 32 andsaw blade 20 over the entire adjustment range of rack and pinion fenceassembly 30. Indicator 160 comprises a stationary lens 162, a firstscale 164 and a second scale 166. Stationary lens 162 is fixedly securedto work table 14 in such a position that it does not interfere with themovement of rack and pinion fence assembly 30. Stationary lens 162 iscapable of being adjusted in order to initially set the width indicatorprovided by indicator 160 by means described below. Stationary lens 162includes a primary pointer 168 positioned adjacent a first viewingaperture 170 and a secondary pointer 172 positioned adjacent a secondviewing aperture 174. The positions of apertures 170 and 174 are offsetas shown in FIGS. 10A through 10C in order to allow viewing scales 164and 166 as will be described later herein. The distance between primarypointer 168 and secondary pointer 172 is a pre-specified distance. Inone embodiment, this distance is five inches.

First scale 164 is fixedly secured to or is embossed into outer rail 112of front tubular side rail assembly 40. First scale 164 is graduatedinto specified increments and extends along outer rail 112 a specifieddistance. In one embodiment, first scale 164 extends for twenty inchesand is graduated into one-sixteenth inch increments. The position offirst scale 164 on outer rail 112 is such that first scale 164 can beviewed through first viewing aperture 170 when first scale 164 islocated beneath stationary lens 162.

Second scale 166 is fixedly secured to or is embossed into outer rail112 of front tubular side rail assembly 40 adjacent to first scale 164.Second scale 166 is graduated into specified increments and extendsalong outer rail 112 a specified distance. In one embodiment, secondscale 166 extends for five inches and is graduated into one-sixteenthinch increments. One embodiment sets the length of second scale 166equal to the length between primary pointer 168 and secondary pointer172 but is to be understood that the length of second scale 166 can bedifferent than the pointer distance. This position of second scale 166adjacent to first scale 164 on outer rail 112 is such that second scale166 can be viewed through second viewing aperture 174.

FIG. 10A illustrates schematically the initial adjustment for indicator160. First, fence body 32 of fence assembly 30 is positioned adjacent tosaw blade 20. At this point, stationary lens 162 is adjusted to positionprimary pointer 168 over the "0" mark on the first scale 164 as viewedthrough aperture 170. Stationary lens 162 is then secured in this "zero"position. This "zero" adjustment by the operator is required after eachchange of cutting tool or any time that indicator 160 is out ofadjustment. Stationary lens 162 is preferably provided with one or moreslots and corresponding attachment bolts to provide for the "zero"position adjustment. The adjustment is made by loosening thecorresponding attachment bolts and moving stationary lens 162longitudinally. Once positioned at the "zero" reading, the correspondingattachment bolts are again tightened to secure lens 162 in place.Alternatively, this "zero" position adjustment can be provided for byother means known well in the art. Any adjustment to the distancebetween fence body 32 and saw blade 20 by the movement of fence body 32will be indicated by pointers 168 or 172 through apertures 170 and 174respectively.

FIG. 10B illustrates schematically a setting where the distance betweenfence body 32 and saw blade 20 is nine inches. Rack and pinion fenceassembly 30 is moved to the right of saw blade 20 until primary pointer168 is positioned adjacent the nine inch marking on first scale 164 asviewed through aperture 170. At this point, fence body 32 is locatednine inches from the edge of saw blade 20 and a rip cut is set whichproduces a nine inch wide piece of cut material.

Due to the fact that rack and pinion fence assembly 30 can positionfence body 32 further from saw blade 20 than the prior art fenceassemblies, second scale 166, secondary pointer 172 and second aperture174 have been incorporated into indicator 160. FIG. 10C illustratesschematically, the crossover point between first scale 164 and secondscale 166 which, in the preferred embodiment, is when the distancebetween fence body 32 and saw blade 20 is twenty inches. When fenceassembly 30 is adjusted to beyond twenty inches from saw blade 20, firstscale 164 will no longer be able to be aligned with primary pointer 168due to the fact that the increased adjustment of fence assembly 30causes first scale 164 to move beyond primary pointer 168 and eventuallyout of view through first viewing aperture 170. When this occurs, secondscale 166 can be aligned with secondary pointer 172 as viewed throughaperture 174 for the remaining adjustment distance of fence assembly 30.While FIG. 10C illustrates the simultaneous crossover from first scale164 to second scale 166, it is within the scope of the present inventionto include an amount of overlap between the two scales 164 and 166 suchthat the same distance will be indicated in both apertures 170 and 174for the overlapping distance. The operation of second scale 166,secondary pointer 172 and second aperture 174 is identical to thatdescribed above for first scale 164, primary pointer 168 and firstaperture 170. The adjustment of fence assembly 30 can thus be indicatedto the end of second scale 166 at which point pinion gears 152 come tothe end of racks 140.

With reference to FIG. 27 a second embodiment of a cutting widthadjustment mechanism is shown. The mechanism includes transparentL-shaped bracket 270 having a cross-hair 272 disposed within an upperhorizontal portion, and two elongated slots 274 disposed in the lowervertical portion. Bracket 270 rests upon front movable rail 360 near oneend and is secured thereto by screws 276 disposed through slots 274 andcorresponding holes formed in rail 360. The inner ends of screws 276 arereceived within the open portion of C-shaped stationary rail 356. Scale278 is formed integrally with table 14, and is positioned between thefront edge of table 14 and rails 356 and 360.

When fence 338 is moved adjacent to blade 20, bracket 270 and inparticular, cross-hair 272, generally points to zero on scale 278. Whenfence assembly 338 is moved by movement of outer rails 360 so as to bespaced from blade 20, cross-hair 272 moves an identical distance andthus indicates the width of cut on scale 278. The provision of slots 274and screws 276 allow for adjustments in the zero position of cross-air272. When screws 272 are loosened, bracket 270 may be slid along rail360 for a distance generally equal to the length of slots 272. When thedesired position is obtained, the screws are tightened. The zeroposition of scale 278 may be adjusted to accommodate saw blades havingdifferent kerf thicknesses, as well as the use of auxiliary fences. Forexample, pieces of wood may be secured to the front of fence assembly toact as an auxiliary fence.

FIGS. 11A and 11B illustrate another embodiment of the presentinvention. A fence assembly 230 is Identical to fence assembly 30 withthe exception of a secondary fence body 232 which is pivotably securedto fence body 32. In certain foreign countries, safety regulations donot permit the rip fence to extend on both sides of the center axis ofthe cutting tool. Thus, secondary fence 232 must not extend through avertical plane extending perpendicular to saw blade 20 and passingthrough the axis of rotation of saw blade 20. A low cost solution tothis problem is to incorporate secondary fence body 232 into fence body32. Fence body 232 is pivotable with respect to fence body 32 about anaxis 234 as shown by arrow 236 between a first position as shown insolid line in FIG. 11A and a second position as shown in dot-dash linesin FIG. 11A. When fence 32 is positioned on the right side of saw blade20 and fence body 232 is located in its first position as shown in FIG.11A, fence body 232 extends from front mount 36 to the center of sawblade 20 but not beyond the center of saw blade 20. When fence 32 ismoved to the left side of saw blade 20 and fence body 232 is located inits second position as shown in FIG. 11B, fence body 232 now extendsform rear mount 38 to the center of saw blade 20 but not beyond thecenter of saw blade 20. The function and operation of fence assembly 230is identical to that described above for fence assembly 30. Although notshown in the drawings, fence body 232 could also incorporate a pivotablesupport similar to pivotable support 34 of fence assembly 30 to providefor additional support of the article being cut when fence body 232 ispositioned beyond work table 14. It is also within the scope of thepresent invention to have pivotable support 34 of fence assembly 30 ofsuch a dimension that it supports fence body 232 and the article beingcut when fence body 232 is added to fence body 32 and is positionedbeyond work table 14.

FIGS. 12A and 12B illustrate a structure which can be incorporated intorack and pinion fence assembly 30 in order to limit the travel of outerrail 112 with respect to inner rail 110. Outer rail 112, shown in FIG.12A, includes rack 140 which includes the plurality of rack teeth 146extending over the entire exposed surface of the rack. Rack teeth 146are designed to mate with pinion gear 152 in order to longitudinallymove outer rail 112 with respect to inner rail 110 due to the rotationof pinion gear 152.

In order to limit the travel of outer rail 112 with respect to innerrail 110 in either direction, rack 140 is provided with an enlargedtooth 147 located at each end of rack 140. As shown in FIG. 12B, piniongear 152 includes a plurality of teeth 149 which mesh with rack teeth146. When pinion gear 152 comes to either of the ends of rack 140, oneof the pinion gear teeth 149 contacts enlarged tooth 147 on rack 140prohibiting additional movement of outer rail 112. The contact betweentooth 149 and enlarged tooth 147 is designed to occur at the tip of geartooth 149 rather than on one of the faces of gear tooth 149. This tipcontact causes the contact force to be applied normally to the end ofthe tooth 149 and thus creates a force which is normal to the tooth oralong a radial line to minimize any type of deformation of gear tooth149, eliminate damage to the faces of gear tooth 149 and provide linecontact between the two gear teeth such that the tendency of pinion gear152 to roll over rack 140 is eliminated.

FIG. 13 shows another embodiment of the present invention. Theembodiment shown in FIG. 13 operates in a similar manner to that shownin FIG. 2, with the differences between the two embodiments being in theconfiguration of the individual components. Rack and pinion fenceassembly 330 comprises a rack and pinion assembly 332, a pair oftelescoping tubular side rail assemblies 334 and 336 and an elongatedfence assembly 338.

The present invention allows the fence assembly to be moved over a rangeof lengths which exceeds the length of the stationary rails. The fenceassembly may be positioned outwardly of at least one side edge of thework table without requiring that the stationary rails extend outwardlyof this side edge. Preferably, the fence assembly can be moved beyondthe width of the work table, outwardly of either side edge, withoutrequiring that the stationary rails have a length which is greater thanthe width of the table to provide for such movement. Further, the fencemay be connected to both front and rear movable rails whichtelescopically engage and slide over front and rear stationary rails.The front and rear movable rails are interconnected, for example, by arack and pinion mechanism or a system of pulleys, which ensure thatmovement of one movable rail causes an equal movement of the othermovable rail. Thus, the fence may be maintained parallel to the sawblade as t is moved relative thereto.

Referring now to FIG. 14, rack and pinion assembly 332 comprises a frontpinion gear 340, a rear pinion gear 342, a pinion shaft 344, a frontbearing mount 346 and a rear bearing mount 348. Front and rear piniongears 340 and 342 are fixedly secured to pinion shaft 344 for rotationtherewith. Pinion gears 340 and 342 engage telescoping side railassemblies 334 and 336 as will be described later herein. Pinion shaft344 extends through front bearing mount 346 and rear bearing mount 348which provide for the rotation of pinion shaft 344. Adjustment wheel 154is secured to pinion shaft 344 to facilitate the movement of side railassemblies 334 and 336 in a similar manner to that described above forrack and pinion assembly 30. Front pinion bearing mount 346 is mountedto the underside of work table 14 by a pair of screws 350. Rear pinionbearing mount 348 is mounted to a slotted adjustment plate 352 by a pairof screws 350. Adjustment plate 352 includes a pair of slotted apertures354 which are utilized to mount adjustment plate 352 and thus rearpinion bearing mount 348 to the underside of work table 14 using a pairof screws 351. Slotted apertures 354 allow for the adjustment of thetransverse position of rear pinion gear 342 with respect to front piniongear 340 thus providing a mechanism for ensuring that fence 422 isparallel to saw blade 20. As shown in exaggeration in FIG. 14A, withbolts 351 generally centered in slotted apertures 354, fence 422 may notbe parallel to blade 20. By loosening bolts 351 and moving plate 352 andthus bearing mount 348 laterally to the position shown in exaggerationin FIG. 14B fence 422 may be made parallel to blade 20. In a preferredembodiment, slotted apertures 354 will allow the axis of the pinionshaft 344 to be shifted by 1/4°.

Referring now to FIGS. 15 through 20, front and rear telescoping tubularside rail assemblies 334 and 336 are each comprised of fixed inner rail356, a glide strip 358 and slidable outer rail 360. Inner rail 356 is agenerally C-shaped tubular member with square edges having a specifiedlength which, in the preferred embodiment, is generally equal to thewidth of work table 14. Inner rail 356 is connected to work table 14using a plurality of fasteners 362 which are spaced along the entirelength of inner rail 356 in a similar manner to that shown for innerrail 11 0 of assembly 30. Alternately, rails 356 may be formedintegrally with table 14. As shown in FIG. 20, fasteners 362 include abolt 364, a nut 366 and a bushing 368. Bolt 364 extends through innerrail 356 and through a bracket 370 which is an integral part of or issecured to work table 14. Bushing 368 is located between inner rail 356and bracket 370 with the assembly being secured by nut 366 beingthreadably received on bolt 364. Access to each bolt 364 is provided bythe open end of C-shaped tubular inner rail 356. Inner rail 356 of siderail assembly 334 is connected to the front of work table 14 generallyparallel to front edge 48 of work table 14 while an identical inner rail356 of side rail assembly 336 is connected in a similar manner to therear of work table 14 generally parallel to rear edge 60. Preferablyboth inner rails 356 extend along the entire width of work table 14 toprovide the maximum amount of support for outer rails 360 while stillmaintaining a minimized envelope for table saw 10 for both storage andportability. However, inner rails 356 may extend for less than theentire width of table 14. glide strip 358 is wrapped around inner rail356 to facilitate the movement of outer rail 360 with respect to innerrail 356. In the preferred embodiment, glide strip 358 is made of UHMWpolyethylene.

Outer rail 360 is a generally C-shaped tubular member which is slidinglyreceived over inner rail 356 and slide strip 358. As shown in FIGS. 13and 14, the external face of each outer rail 360 is adapted at each endto locate and secure elongated fence assembly 338 to side railassemblies 334 and 336. Each end of outer rail 360 includes an aperture372 and a stud 374 which mate with fence assembly 338 as will bedescribed later herein. One aperture 372 and one stud 374 are located atthe opposite ends of outer rail 360 to permit the positioning of fenceassembly 338 on either side of saw blade 20 to maximize the versatilityof fence assembly 330.

As shown in FIGS. 13 and 14, outer rail 360 includes a rack 376 whichcan be integral with outer rail 360 or it can be a separate componentattached to a lower extending flange of outer rail 360 by a plurality ofscrews. Rack 376 extends over the entire length of outer rail 360. Rack376 includes a plurality of rack teeth 378 which extend over the entiresurface of the rack. Rack teeth 378 are designed to mate with piniongears 340 and 342 in a similar manner to that described above forassembly 30. The mating of racks 376 of each outer rail 360 with piniongears 340 and 342 disposed on a common shaft 344 ensures that the outerrail of one of side rail assemblies 334, 336 will always move an equaldistance with the outer rail of the other side rail assembly. Thus, eachend of fence assembly 338 will always be displaced an equal distancewhenever the fence assembly is moved due to the movement of the outerrails. Accordingly, the longitudinal surface of fence body 422 ismaintained parallel to the saw blade. The method illustrated in FIGS.12A and 12B for limiting the travel of outer rail 360 with respect toinner rail 356 may also be incorporated into rack and pinon fenceassembly 330 if desired.

FIGS. 15 through 17 also illustrate an over-enter toggle lock assembly380 which locks outer rails 360 to inner rails 356 when outer rails 360have been moved to a desired location. Lock assembly 380 comprises alock lever 382, a lock arm 384, a rear lock link 386, a front lock link388, a rear lock pin 390 and a front lock pin 392. Lock lever 382 ispivotably secured to work table 14 by a pair of bearing blocks 394 whichare bolted to the underside of work table 14. Lock lever 382 includes aforward arm 398 which is utilized to actuate lock assembly 380 from thefront of table saw 10 and a rear arm 400 which is pivotably secured tolock arm 384. Lock arm 384 includes a slot 402 at one end which receivesrear arm 400 and an aperture 404 at the opposite end which receives rearlock link 386. Rear lock link 386 is a threaded rod which mates withlink arm 384 at one end and is pivotably connected in a horizontal planeto rear lock pin 390 at its opposite end. Front and rear lock pads 418and 408 are secured to table 14 adjacent slidable rails 360. In thepreferred embodiment, pads 418 a nd 408 are flexible and are made ofsheet steel. Pads 418 and 408 are designed to flex inwardly out ofcontact with outer rails 360, thereby allowing outer rails 360 to slidefreely over friction pads 358, as shown in FIG. 15.

Rear lock pin 390 extends through an aperture 406 in work table 14adjacent to rear lock pad 408. As described further below, pin 390 maybe moved into contact with pad 408 to lock outer rail 360 of side railassembly 336 to its corresponding inner rail 356. An adjusting nut 410is threadingly received on rear lock link 386 and a plurality ofBelleville disc springs 412 are disposed between adjusting nut 41 0 andlock arm 384. Disc springs allow for the adjustment to the load whichneeds to be applied to lock lever 382 to actuate lock assembly 380 aswill be described later herein.

Lock arm 384 also includes a pair of flanges 414 which are located onthe end of lock arm 384 adjacent to slot 402. Front lock link 388 ispivotably connected to flange 414 at one end and pivotably connected tofront lock pin 392 at the opposite end. Front lock pin 392 extendsthrough an aperture 416 in work table 14 adjacent to front lock pad 418and may be moved into contact with pad 418 to lock outer rail 360 ofside rail assembly 334 to its corresponding inner rail 356.

FIGS. 18 and 19 illustrate the locking pivotal connection between frontlock link 388 and flange 414 of lock arm 384. It is to be understoodthat a similar locking pivotal connection is provided at the pivotalconnection between front lock link 388 and front lock pin 392 andbetween rear lock link 386 and rear lock pin 390.

Front lock link 388 is provided with a pair of formed upstanding tabs387. Flanges 414 each include a generally circular aperture 389 having apair of slots 391 corresponding with the pair of tabs 387. As shown inFIG. 18, front lock link 388 is inserted through aperture 389 while thepair of tabs 387 are in alignment with the pair of slots 391. Once link388 is inserted through each flange 414, it is rotated to its workingposition as shown in FIG. 19. The working position for lock link 388positions the pair of tabs 387 out of alignment with the pair of slots391 thus prohibiting removal of lock link 388 from lock arm 384.

The released position of over-center toggle lock assembly 380 is shownin FIG. 15. In this position, the pivot point A between front lock pin392 and front lock member 388, the pivot point B between lock arm 384and front lock member 388, and the pivot point C between rear lock link386 and rear lock pin 390 are not in alignment. As the mechanism ismoved to its locked position by rotating arm 398 downwardly, as shown inFIG. 16, the above pivot points are moved more in line. As they aremoved in line, the overall length of lock arm 384, lock links 386, 388and pins 390,392 is increased such that pins 390, 392 are movedoutwardly into contact with pads 408, 418 which are pushed into contactwith and lock outer rails 360. Disc springs 412 are compressed duringthis movement, and exert a locking force on arm 384, and links 386, 388.The provision of springs 412 assists in the locking action. However, thespring force tends to push the pivot points out of line, accordingly, inorder to lock or "park" over-enter toggle lock assembly 380, the pivotpoints are allowed to move slightly past the in-line position until locklinks 388 come to rest against a stop 420 located on lock arm 384. Thespring force will attempt to move the pivot points more out-of-line,i.e., upwardly towards the table, and thus hold assembly 380 in thelocked or "parked" position.

Referring now to FIGS. 13, 13A and 21, elongated fence assembly 338comprises an elongated fence body 422, a front fence mount 424, a rearfence mount 426 and a pivotable support member 428. Fence body 422 is anelongated hollow rectangular member which provides a flat guide surface430. Fence body 422 is sized to extend beyond both the front and rearlongitudinal edges 48 and 50 of work table 14. Fence body 422 is securedat its opposite ends to front fence mount 424 and rear fence mount 426using a pair of bolts 432. The attachment of fence mounts 424, 426 tofence body 422 will be described later herein. Fence body 422 includesupper and lower circular apertures 444 at each end extending through thewall of fence body 422 opposite to guide surface 430. Fence mounts 424,426 include a pair of fingers 440 which extend into the hollow interiorof fence body 422. Each finger 440 include a threaded hole 450 whichaccepts a respective bolt 432. Bolts 432 are inserted into the circularapertures 444 and are threadingly received within threaded holes 450 onthe fingers 440.

Referring now to FIGS. 13, 13A, 14 and 21, fence mounts 424, 426 will bedescribed in greater detail. It is to be understood that rear fencemount 426 is a mirror Image of front mount 424 and the description belowapplies to both front and rear fence mounts 424 and 426. Front fencemount 424 includes a main body 434, an L-shaped bracket 436 whichextends down from body 434, an over-center latch which 438 extendsbetween body 434 and bracket 436 and a pair of fingers 440 which extendinwardly from body 434. Body 434 also includes support ribs 441.L-shaped bracket 436 is designed to mate with a respective outer rail360. L-shaped bracket 436 defines a slot 442 which engages a respectivestud 374 located on the respective outer rail 360 and opening 443 whichcorresponds with aperture 372 in outer rail 360. The engagement betweenstud 374 and slot 442 properly positions fence mounts 424, 426 withrespect to the corresponding outer rail 360. Stud 374 and slot 442 areprovided to more accurately position fence mounts 424, 426 on outer rail360 rather than relying solely on the connection of over-center latch438 to aperture 372. Once slot 442 engages stud 374, over-center latch438 is connected to aperture 372 in outer rail 360 and then moved to itslocked position to secure fence mounts 424, 426 to their respectiveouter rails 360. With reference to FIG. 27, alternative construction ofthe fence mounts is shown as fence mounts 424' and 426'. With referenceto front fence mount 424', a slot 442' extends to the right of theover-center latch in this embodiment.

FIGS. 21A and 21B illustrate over-center latch 438 in cross-section inboth the latched position (FIG. 21A) and the released position (FIG.21B). Over-center latch 438 comprises a latch 488 and a clasp 490. Latch488 is pivotably secured to mount 436 by a pin 492 and clasp 490 ispivotably secured to latch 488 by a pin 494. Clasp 490 is an S-shapedmember which includes a hooked end 496 for mating with aperture 372 tosecure fence mount 424 to outer rail 360. Latch 488 is held in itsdownward or latched position due to a spring force being exerted byclasp 496 and the geometry of over-center latch 438 where pin 494 ispositioned over the center of a line defined by pin 492 and hooked end496 mating with aperture 372.

Over-center latch 438 is released by lifting latch 488 and pivoting pin494 around pin 492 and thus moving pin 494 back over-center and towardsaperture 372. The raising of latch 488 first releases the spring tensionon clasp 490 and then moves hooked end 496 into a position to be removedfrom aperture 372. At this point in the movement of latch 488, clasp 490contacts a camming surface 498 located on fence mount 424. Continuedupward movement of latch 488 causes hooked end 496 to withdraw fromaperture 372 due to the camming action between clasp 490 and cammingsurface 498. Once hooked-end 496 has been withdrawn from aperture.372,removal of fence mount 424 can be accomplished by simply lifting fencemount 424 off of outer rail 360.

FIGS. 21C and 21D illustrate a spring 451 which is designed to beinserted between fence mount 426 of fence assembly 338 and outer rail360 of side rail assembly 336. FIG. 21C illustrates fence assembly 338incorporating biasing spring 451 which is clipped onto rear fence mount426. FIG. 21C further illustrates work table 14 including side railassemblies 334 and 336. Fence assembly 338 is positioned over side railassemblies 334 and 336. Thus, the dimension between opposing faces 453on fence mounts 424 and 426 must always be larger than the dimensionover the outer surfaces 455 on side rail assemblies 334 and 336. Whenthe tolerance stack up is taken into consideration, there could beexcessive clearances provided between fence assembly 338 and side railassemblies 334 and 336. Spring 451, shown in FIG. 21D, includes a body455 having a retaining tab 457 located at opposite sides of body 455.Retaining tabs 457 are designed to encircle the opposite ends of fencemount 426 to retain spring 451 in position against face 453 of fencemount 426. Spring 451 further includes a pair of legs 459 which extendvertically from body 455 and each of which is bent towards the same sideof body 455 as are tabs 457. When assembled to fence mount 426, body 455is spaced away from surface 453 due to both the shape of retaining tabs457 and the shape of legs 459 as shown in FIG. 21C.

When fence assembly 338 is positioned over side rail assemblies 334 and336, legs 459 of spring 451 help to guide the assembly to insure thatspring 451 will be located between face 453 of fence mount 426 andsurface 455 of side rail assembly 336. Once assembled, spring 451 biasesfence assembly 338 away from side rail assembly 336 to remove theclearances between the two members.

Referring to FIGS. 22 and 23, pivotable support member 428 comprises arear pivot arm 460, a front pivot arm 462 and a support plate 464.Pivotable support member 428 provides support for the workpiece at apoint adjacent to guide surface 430 when fence body 422 is positionedbeyond work table 14. Pivotable support member 428 is movable between alower position and a raised position similar to that shown in FIGS. 1, 2and 4 of the previous embodiment. Pivotable support member 428 isprovided with a locking mechanism to lock it in either of the raised orlowered positions as will be described later herein.

Support plate 464 extends;between and is connected to front and rearpivot arms 462 and 460. Front pivot arm 462 is pivotably secured tofront fence mount 424 using a shoulder bolt 466. A coil spring 468 islocated in a spring pocket 470 in front fence mount 424 and operates tobias front pivot arm 462 away from front fence mount 424. Rear pivot arm460 is pivotably secured to rear fence mount 426 also using a shoulderbolt 466. A locking post 472 extends inward from the surface of pivotarm 460 which is adjacent to rear fence mount 426. Locking post 472 isadapted to engage a first locating hole 474 when support member 428 isin its lower position and a second locating hole 476 when support member428 is in its upper position. Rear pivot arm 460 is biased toward rearfence mount 426, and thus post 472 into one of the two locking holes 474and 476, by the load exerted by coil spring 468 acting against frontpivot arm 462. Thus, pivot arm 460 may be locked in either the upper orlower position. This biasing load is transferred to rear pivot arm 460by support plate 464. The distance between front and rear pivot arms 462and 460 is greater than the distance across front and rear fence mounts424 and 426 by a distance which is greater than the height of post 472.Thus, when post 472 is in engagement with one of the two locating holes474 or 476, a gap 478 is created between front pivot arm 462 and frontmount 424. In order to move support member 428 between positions, frontpivot arm 462 is pushed towards front fence mount 424 to release lockingpost 472 from the hole. Support member 428 can then be pivoted to theother position with the subsequent release of rear pivot arm 462 causingengagement of post 472 with the other hole due to the biasing of spring468.

FIG. 22 also illustrates another unique embodiment of the presentinvention. Guide surface 430 of fence body 422 includes a scale 484which is useful when setting the height of saw blade 20. Scale 484 isdesigned to indicate a zero reading at the top of work table 14 andincrease vertically upward. Thus by positioning fence body 422 adjacentto saw blade 20, a direct reading of the depth of cut or height of sawblade 20 is given. Scale 484 is etched onto or machined into surface 430and thus does not interfere with the function or accuracy of surface430.

The telescoping rails of the present invention have sufficient clearancebetween each stationary rail and movable rail disposed thereon toaccommodate the non-straightness of the rails. This clearance can causeexcessive end play of the extended rail as the extended rail movestoward its totally extended position. Thus, it may be desirable, in thepresent invention, to provide a system for stabilizing the extended railas it moves to it fully extended position. FIG. 24A and 24Bschematically represent a stationary rail 500 and a movable rail 502.Stationary rail 500 is adapted to be secured to a work table in asimilar manner shown previously in FIG. 20 for stationary rail 356.Movable rail 502 telescopically engages stationary rail 500 in a similarmanner shown previously for movable rail 360 with sufficient clearancemaintained between the movable and stationary rail to accommodate anynon-straightness. Each end of stationary rail 500 would include anoutwardly extending shim 504 and each end of movable rail 502 wouldinclude an inwardly extending shim 506. Shims 504 contact the innersurface of outer rail 502 while shims 506 contact the outer surface ofinner rail 500. These contact points help stabilize the movable railagainst vertical movement in any extended position of the movable rails.However, shims 504 and 506 must be provided in a manner which allows formovable rail 502 to move from the position shown in FIG. 24A to thatshown in 24B. That is, it is necessary for inwardly extending shims 506to pass through: outwardly extending shims 504.

FIG. 25A illustrates a construction of stationary rail 500 and movablerail 502 which provides shims 504 and 506 which pass through each other.Stationary rail 500 incorporates a steel skeleton 501 and a coveringportion 503. Covering portion 503 is preferably manufactured from anylon based material and is injection molded over skeleton 501 as shown.Covering portion 503 preferably extends over the entire length of rail500 and defines a pair of pads 508 on the upper and lower surfaces ofstationary rail 500 at each end. Each pair of pads 508 defines a channel510 extending longitudinally along the length of stationary rail 500 fora short distance. The pair of pads 508 are designed such that theyslidingly engage the interior surfaces of movable rail 502 to reduce oreliminate the clearances between the two rails. Pads 508 also could be aseparate component assembled to skeleton 501.

FIG. 25B illustrates movable rail 502 incorporating inwardly extendingpads 512 integrally formed as a part of movable rail 502 at each end.One pad 512 is formed into an upper wall of rail 502 while the secondpad 512 is formed into the lower wall of rail 502. Pads 512 may beformed by stamping the rails inwardly in the roll forming process of therails. Pads 512 are positioned to align with channels 510 defined bypads 508 such that movable rail 502 is allowed to move outwardly beyondstationary rail 500 in both directions as is schematically illustratedin FIGS. 24A and 24B. Pads 508 function as shims 504 and pads 512function as shims 506 as described with reference to FIGS. 24A and 24B.Thus, the contact of pads 508 and 512 with outer rail 502 and inner rail500, respectively, stabilizes the outer rails in the extended position.In addition, it is within the scope of the present invention to form pad508 into each end of rail 500 by stamping, as described below for pads518 and movable rail 502.

FIG. 26 illustrates a preferred embodiment of a stabilizing systemaccording to the present invention. A stationary rail 520 defines a pairof slots 522 extending parallel to each other and longitudinally intostationary rail 520 to define a tab 524. Lower wall 528 incorporates anoutwardly stamped protrusion 525. Disposed between tab 524 andprotrusion 525 is a wedge assembly 530. Wedge assembly 530 comprises abase 532, a wedge 534 and a bolt 536. Base 532 is a C-shaped componenthaving upper, lower and vertical legs linked by a pair of living hinges538 and a threaded bore 540. Base 532 is inserted into the open end ofrail 520 such that one living hinge 538 is adjacent upper wall 526 andthe second living hinge 538 is adjacent lower wall 528. The width ofbase 532 is selected to be equal to or slightly less than the width oftab 524. After insertion of base 532 into rail 520, wedge 534 ispositioned into the open portion of base 532 and bolt 536 is insertedthrough a hole 542 in wedge 534 and threadably engaged with threadedbore 540. As bolt 536 is tightened, wedge 534 reacts against the openupper and lower legs of C-shaped base 532 to expand the open legs whichreact against tab 524 to urge tab 524 outward to reduce or eliminate theclearance between stationary rail 520 and a movable rail (not shown).The expansion of C-shaped base 532 is preferably set prior to themovement of the movable rail or at the manufacturing facility but theexpansion can be set by the operator at any time simply by accessingbolt 536. Base 532 is a molded plastic part. In another embodiment, base532 and wedge 534 can be molded integrally such that wedge 534 is linkedto the upper and lower legs by a thin ligament.

As shown in FIGS. 13 and 14, front bearing mount 346 is rigidly securedto the underside of work table 14 using the pair of screws 350. Rearbearing mount 348 is secured to adjustment plate 352 using the pair ofscrews 350 and adjustment plate 352 is rigidly secured to the undersideof work table 14 using the pair of screws 351. The connection of bearingmounts 346 and 348 thus rigidly secure pinion shaft 344 to work table14. Such a rigid connection may result in backlash when the movablerails are moved.

FIGS. 28 and 29 illustrate an alternative embodiment for the bearingmount. Bearing mount 560 spring loads or biases pinion shaft 344upwardly towards table 14 such that the pinions are urged against theracks, as shown with respect to springs 156 in FIG. 9. However, bearingmounts 560 allow only a limited vertical movement, thereby avoidingbacklash and simultaneously ensuring that the pinion gears do not becomedisengaged from the rack.

Bearing mount 560 comprises a plastic bearing 562, a sheet metal cover564 and a coil spring 566. Bearing 562 is preferably manufactured from alow friction plastic such as Delrin® manufactured by DuPont and includesa base 568, a guide bearing 570 and a flexible arm or hinge 572 disposedbetween base 568 and guide bearing 570. Base 566 defines a pair ofapertures 574 which accept screws 350 when bearing mount 560 is beingsecured to the underside of work table 14 or to adjustment plate 352.Guide bearing 570 defines an aperture 576 extending through bearing 570for accepting pinion shaft 344. Guide bearing 570 is pivotable about ahorizontal axis with respect to base 568 due to the connection to base568 by hinge 572. Bearing 562 thus allows vertical movement of shaft 344but eliminates lateral movement of the shaft.

Sheet metal cover 564 is a cup shaped member defining a pair of sidewalls 578 and a pair of end walls 580. Side walls 578 each define aslotted aperture 582 which aligns with aperture 576 of bearing 570 afterassembly of bearing mount 560. Side walls 578 each also define a pair ofdetents 584 which snap into a corresponding pair of slots 586 locatedwithin base 568 to retain the assembly of bearing mount 560 prior to theinsertion of screws 350. End walls 580 each define a flange 588 havingan aperture 590 which is designed to align with a respective aperture574 for securing bearing mount 560 to the under side of work table 14.Coil spring 566 is disposed between cover 564 and bearing 562 andoperates to urge guide bearing 570 towards base 568, and towards worktable 14. A spring retainer 592 is integrally formed with guide bearing570.

The assembly of bearing mount 560 begins by locating coil spring 566 onretainer 592 and inserting plastic bearing 562 into cover 564. Bearing562 is inserted into cover 564 until the two pairs of detents 584 snapinto their corresponding slots 586 to retain bearing 562 within cover564 against the load exerted by coil spring 566. Pinion shaft 344 canthen be inserted through aligned apertures 582 and 576 and the assemblyof bearing mount 560 and pinion shaft 344 can be secured to the underside of work table 14 or adjustment plate 352 by inserting screws 350through aligned apertures 574 and 590 and threadably engaging them withtheir respective threaded bores. Accordingly, shaft 344 is urged towardstable 14 by coil spring 566 and thus, pinions 340, 342 are urged intoengagement with rack 378. However, vertical movement of shaft 344 andthus pinions 340, 342 is limited by apertures 576, precluding thepinions from becoming disengaged from the rack.

FIGS. 30A through 30C schematically illustrate another embodiment of thepresent invention which allows the synchronized movement of thetelescoping rail assemblies for a table saw. FIG. 30A schematicallyillustrates a work table 614 which is similar to work table 14 describedabove. A pair of telescoping tubular side rail assemblies 634 and 636are secured to work table 614. Side rail assemblies 634 and 636 aresimilar in construction to side rail assemblies 334 and 336 in that theycomprise an inner rail 656, a slide strip (not shown) and an outer rail660. Side rail assemblies 634 and 636 are different from side railassemblies 334 and 336 in that outer rail 660 of each side rail assemblydoes not include rack 376. Instead of utilizing a rack and pinion systemto ensure the synchronous movement of rail assemblies 634 and 636, asystem of cables and pulleys designated generally by the referencenumeral 610 are used.

System 610 comprises four pulleys 612a, 612b, 612c and 612d disposed ateach corner of the undersurface of work table 614 and a pair of cables616a and 616b extending between outer rails 660 and being circuitouslyrouted through pulleys 612a-612d. As shown in FIG. 30A, cable 616aextends from a first end 662 of outer rail 660 associated with railassembly 634, winds around pulley 612b, winds around pulley 612d andterminates at an opposite end 664 of outer rail 660 associated with railassembly 636. Cable 616b extends from an opposite end 666 of outer rail660 associated with rail assembly 634, winds around pulley 612a, windsaround pulley 612c and terminates at a first end 668 of outer rail 660associated with rail assembly 636. Thus, when rail assemblies 634 and636 are moved to the left as shown in FIG. 30B, the synchronous movementof the rail assemblies is provided by cables 616a and 616b and theircircuitous route through pulleys 612a-612d. In a similar manner, whenrail assemblies 634 and 636 are moved to the right as shown in FIG. 30C,the synchronous movement of the rail assemblies is again provided bycables 616a and 616b and their circuitous routing through pulleys612a-612d. Since movement of one rail 660 forces an equal movement ofthe other rail 660 due to the fact that each cable is connected to bothrails 660, the fence is maintained parallel to the saw blade.

FIGS. 31A through 31C illustrate another embodiment of a cablesynchronous assembly which is designated generally by the referencenumeral 700. Cable synchronous assembly 700 comprises work table 714,side rail assemblies 634 and 636, tension adjustment assembly 702,alignment adjustment assembly 704 and cables 716a and 716b. Cable 716aextends from first end 662 of outer rail 660 associated with railassembly 634, winds through tension adjustment assembly 702, throughalignment adjustment assembly 704 and terminates at opposite end 664 ofouter rail 660 associated with rail assembly 636. Cable 716b extendsfrom opposite end 666 of outer rail 660 associated with rail assembly634, winds through tension adjustment assembly 702, through alignmentadjustment assembly 704 and terminates a first end 668 of outer rail 660associated with rail assembly 636. Thus, rail assemblies can be moved tothe left or to the right (as shown in FIG. 31A) with the synchronousmovement of rail assemblies 634 and 636 being provided by cables 716aand 716b, tension adjustment assembly 702 and alignment adjustmentassembly 704.

Referring now to FIG. 31 B, tension adjustment assembly 702 comprises amounting plate 720, a pair of pivoting arms 722, a pair of pulleys 724and an adjustment screw 726. Mounting plate 720 is secured to the underside of table 714 by a plurality of bolts 728 and a pivot bolt 730.Pivot bolt 730 extends generally perpendicular, outward from mountingplate 720 to provide a pivotal mounting for pivoting arms 722. Eachpivoting arm 722 pivots about bolt 730 and rotatably supports arespective pulley 724. Adjustment screw 726 includes a knob 732, a firstthreaded portion 734, an anchoring flange 736 and a second threadedportion 738. Adjustment screw 726 is rotatably secured to mounting plate720 by anchoring flange 736 being rotatably received by an anchor 740fixedly secured to or an integral part of mounting plate 720. Firstthreaded portion 734 threadingly engages a nut 742 which is secured toone of the pivoting arms 722 such that rotation of adjustment screw 726causes pivotal movement of its respective pivoting arm 722. Secondthreaded portion 738 threadingly engages a nut 744 which is secured tothe other pivoting arm 722 such that rotation of adjustment screw 726causes pivotal movement of its respective pivoting arm 722. As shown inFIG. 31B, threaded portion 734 and nut 742 are threaded opposite tothreaded portion 738 and nut 744. (One is a right handed thread and theother is a left handed thread). Thus, rotational movement of adjustmentscrew 726 will cause pivoting arms 722 to pivot in opposite directionscausing a tightening or loosening of cables 716a and 716b depending onwhich direction adjustment screw 726 is rotated.

Referring now to FIG. 31C, alignment adjustment assembly 704 comprisesan additional mounting plate 720, an additional pair of pivoting arms722, an additional pair of pulleys 724 and an adjustment screw 726'.Thus, alignment adjustment assembly 704 is similar to the abovedescribed tension adjustment assembly 702 except that adjustment screw726 has been replaced by adjustment screw 726'. Adjustment screw 726'includes a knob 732, a first threaded portion 734', anchoring flange 736and a second threaded portion 738'. Adjustment screw 726' is rotatablysecured to mounting plate 720 in a similar manner to that describedabove for adjusting screw 726. First threaded portion 734' threadablyengages a nut 742' which is secured to one of the pivoting arms 722 suchthat rotation of adjustment screw 726' causes pivotal movement of itsrespective pivoting arm 722. Second threaded portion 738' threadinglyengages a nut 744' which is secured to the other pivoting arm 722 suchthat rotation of adjustment screw 726' causes pivotal movement of itsrespective pivoting arm. As shown in FIG. 31C, threaded portion 734' andnut 742' are threaded the same as threaded portion 738' and nut 744'(both are right or left handed thread). Thus, rotational movement ofadjustment screw 726' will cause pivoting arms 722 to pivot in the samedirection causing lateral adjustment to rail assembly 636 which adjuststhe alignment between rail assembly 634 and rail assembly 636. Thisadjustment causes one end of fence assembly 338 to move relative to theother, thereby allowing the parallelism between the blade and the fenceto be adjusted.

FIGS. 32A-C illustrate additional embodiments of a rack and pinionsynchronous adjustment system where the fence is maintained in aparallel relationship to the saw blade but the fence cannot be adjustedbeyond the surface of the work table.

FIG. 32A illustrates a table saw 800 comprising a powered saw blade 802,a work table 804, a pair of racks 806, and a fence assembly 808. Racks806 are fixedly secured to opposite sides of work table 804 and extendlongitudinally along the entire length of work table 804 generallyperpendicular to saw blade 802. Fence assembly 808 comprises a pinionshaft 810, a pair of bearing mounts 812, an elongated fence 814, a pairof pinion gears 816 and a knob 818. Pinion shaft 810 extends across worktable 804 generally parallel to saw blade 802. Pinion shaft 810 extendsthrough and is rotatable with respect to each of the bearing mounts 812.Elongated fence 814 is fixedly secured to bearing mounts 812 such thatit extends generally parallel to pinion shaft 810 and saw blade 802.Pinion gears 816 are fixedly mounted to pinion shaft 810 at a positionoutboard of fence 814 and spaced a distance equal to the distancebetween racks 806 when fence assembly 808 is located on table saw 800.Knob 818 is fixedly secured to pinion shaft 810 generally outboard ofone of the pinion gears 816 at the front side of table saw 800. Whenfence assembly 808 is located on table saw 800 as shown in FIG. 32A,rotation of knob 818 causes simultaneous movement of pinion shaft 810and pinion gears 816. The simultaneous rotation of pinion gears 816causes lateral motion of fence assembly 808 with respect to saw blade802. The rack and pinion relationship between fence assembly 808 andwork table 804 ensures the parallel movement of fence assembly 808.Alternatively, movement of fence 814 along the surface of table 804causes an equal rotation of pinion gears 816, ensuring that both sidesof fence 814 move an equal distance, and thereby maintaining theparallelism between fence 814 and blade 802.

FIG. 32B illustrates a table saw 830 comprising a powered saw blade 832,a work table 834, a pair of racks 836 and a fence assembly 838. Racks836 are fixedly secured to opposite sides of work table 834 and extendlongitudinally along the entire length of work table 834 generallyperpendicular to saw blade 832. Fence assembly 838 comprises anelongated fence 840, a gear shaft 842, an Idler shaft 844, and a gearshaft 846. Elongated fence 840 is located atop of work table 834 andextends generally parallel to saw blade 832. Geared shaft 842 isrotatably secured to fence 840 at the front of table saw 830. Gearedshaft 842 includes a fixedly secured front drive gear 848, a fixedlysecured rear drive gear 850 and a knob 852. Idler shaft 844 is alsorotatably secured to fence 840 at the front of table saw 830. Idlershaft 844 includes a front pinion gear 854 which meshes with both frontdrive gear 848 and one of the racks 836. Geared shaft 846 is rotatablysecured to fence 840 at the rear of table saw 830. Geared shaft 842includes a fixedly secured rear drive gear 856 and a fixedly securedrear pinion gear 858. Rear pinion gear 858 meshes with the other rack836. Rear drive gear 850 is drivingly connected to rear drive gear 856by an endless toothed belt 860. When fence assembly 838 is located ontable saw 830 as shown in FIG. 32B, rotation of knob 852 simultaneouslyrotates front drive gear 848 and rear drive gear 850. The rotation offront drive gear 848 causes rotation of front pinion gear 854 whichcauses lateral movement of the front of fence assembly 838. Thesimultaneous rotation of rear drive gear 850 causes rotation of reardrive gear 856 through belt 860 which cause rotation of rear pinion gear858 which causes lateral movement of the rear of fence assembly 838. Thesimultaneous rotation of both front pinion gear 854 and rear pinion gear858 results in the parallel movement of fence assembly 838 along worktable 834.

FIG. 32C illustrates a table saw 870 comprising a powered saw blade 872,a work table 874, a pair of racks 876 and a fence assembly 878. Racks876 are fixedly secured to opposite sides of work table 834 and extendlongitudinally along the entire length of work table 834 generallyperpendicular to saw blade 872. Fence assembly 878 comprises anelongated fence 880, a pinion shaft 882, a pair of drive gears 884 and apair of compound pinion gears 886. Elongated fence 880 is a hollowrectangular structure which extends across work table 874 generallyparallel to saw blade 872. The length of fence 880 is designed to alloweach end to extend beyond the Width of work table 874 and racks 876 andeach end of fence 880 includes a flange 888 which extends down overracks 876 to rotatably mount compound pinion gears 886. Pinion shaft 882is rotatably mounted to both ends of fence 880 and thus also extendsgenerally parallel to saw blade 872. Drive gears 884 are fixedly mountedon pinion shaft 882 at a position adjacent the ends of fence 880.Compound pinion gears 886 are each rotatably mounted to a respectiveflange 888 such that they are each meshed with a respective drive gear884 and a respective rack 876. A knob (not shown) is fixedly secured topinion shaft 882 at the front of table saw 870. Rotation of the knobcauses simultaneous rotation of drive gears 884 which causessimultaneous rotation of compound pinion gears 886 which causessimultaneous lateral movement of the front and rear of fence assembly878. The simultaneous rotation of both compound pinion gears 886 resultsin parallel movement of fence assembly 878 along work table 834.

While the above detailed description describes the preferred embodimentof the present invention, it should be understood that the presentinvention is susceptible to modification, variation and alterationwithout deviating from the scope and fair meaning of the subjoinedclaims.

What is claimed is:
 1. A fence assembly comprising:a fence having firstand second mounts disposed at opposite ends of said fence, said fencedefining a guiding surface having a bottom edge; and a support memberpivotably secured to said fence, said support member being pivotablebetween a first position adjacent said guiding surface and a secondposition on an axis extending between said first and second mountsgenerally parallel to said fence, said support member defining a supportsurface generally perpendicular to said guiding surface when said fenceis in said first position, said support member being located below saidbottom edge of said guiding surface when said support member is in saidfirst position.
 2. The fence assembly according to claim 1 wherein, saidsupport member is releasably looked into said first position.
 3. Thefence assembly according to claim 1 wherein, said support member ispivotably secured to said first and second mounts.
 4. A fence assemblycomprising:a first rail; a second rail spaced from and disposedgenerally parallel to said first rail; a fence disposed between andconnected to said first and second rails, said fence defining a guidingsurface having a bottom edge; and a support member pivotably secured tosaid fence, said support member being pivotable between a first positionand a second position on an axis extending between said first and secondrail generally parallel to said guiding surface, said support memberdefining a support surface generally perpendicular to said guidingsurface when said fence is in said first position, said support memberbeing located below said bottom edge of said guiding surface when saidsupport member is in said first position.
 5. The fence assemblyaccording to claim 4 wherein, said fence is adjustably connected to saidfirst rail.
 6. The fence assembly according to claim 5 wherein, saidfence is adjustably connected to said second rail.
 7. A machine toolhaving a base defining a working surface, said machine tool comprising:afirst rail secured to said base; a second rail secured to said base,said second rail being spaced from and generally parallel to said firstrail; a fence disposed between and connected to said first and secondrails, said fence defining a guiding surface; and a support memberpivotably secured to said fence, said support member defining a supportsurface, said support member being pivotable between a first positionwhere said support member is adjacent to said guiding surface and asecond position where said support surface is remote from said guidingsurface, said support surface being generally coplanar with said workingsurface when said support member is in said first position.
 8. Themachine according to claim 7 wherein said support member pivots about anaxis that extends between said first and second rail generally parallelto said guiding surface.
 9. The machine tool according to claim 7,wherein said fence is adjustably connected to said first rail.
 10. Themachine tool according to claim 9, wherein said fence is adjustablyconnected to said second rail.
 11. The fence assembly according to claim7, wherein said support member is releasably locked into said firstposition.
 12. The fence assembly according to claim 7, wherein saidfence includes first and second mounts, said support member beingpivotably secured to said first and second mounts.